SIPTU's National Executive has strongly endorsed Labour to win enough seats "to balance the right in government".

It warned more than 200,000 members in the latest edition of 'Liberty' magazine that Fine Gael could win a majority with only 35pc of the first preference vote, and urged them to back left of centre candidates. But it said opinion polls pointed to a grand coalition of Fine Gael and Fianna Fail.

"It would be the most right-wing government in the history of the State - a combination of those who introduced the ruinous bank guarantee and those who most enthusiastically supported it," it said.

It said there was still the question of a possible Fianna Fáil and Sinn Féin alliance.

However, it said this was "not in prospect" as in order to win enough seats these parties would have to agree a very disciplined transfer voting pact.

The union's leaders told members "we should work towards a left of centre government".

"Its prospects can be enhanced if all of us extend preference votes to those standing on left platforms all the way down the ballot paper," it said.

"The only way of depriving the right of a monopoly of power and thus protecting the basic interests of working people ... is if Labour wins enough seats to balance them in government."